Yeerk
Encyclopedia
Yeerks are a fictional extraterrestrial
Extraterrestrial life in popular culture
In popular cultures, "extraterrestrials" are life forms — especially intelligent life forms— that are of extraterrestrial origin .-Historical ideas:-Pre-modern:...

 species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 from the book and television series "Animorphs
Animorphs
Animorphs is an English language science fiction series of young adult books written by K. A. Applegate and published by Scholastic. Five humans, Jake, Marco, Cassie, Rachel, and Tobias, and one alien, Aximili-Esgarrouth-Isthill , obtain the ability to morph into any animal they touch. They name...

" written by K. A. Applegate and published by Scholastic.

Biology

A Yeerk is a parasite that takes over the body of another being by way of infestation through the ear canal
Ear canal
The ear canal , is a tube running from the outer ear to the middle ear. The human ear canal extends from the pinna to the eardrum and is about 35 mm in length and 5 to 10 mm in diameter....

. It resembles a small, gray-green slug
Slug
Slug is a common name that is normally applied to any gastropod mollusc that lacks a shell, has a very reduced shell, or has a small internal shell...

 about five or six inches long (see The Capture
The Capture (Animorphs)
The Capture, published in 1997 and written by K.A. Applegate, is the sixth book in the Animorphs series. It is narrated by Jake. The Capture is due to be re-releasd by Scholastic in March 2012.-Plot summary:...

, first U.S. print edition page 150). Yeerks in their natural state have decent senses of smell
Olfaction
Olfaction is the sense of smell. This sense is mediated by specialized sensory cells of the nasal cavity of vertebrates, and, by analogy, sensory cells of the antennae of invertebrates...

 and touch, but they are blind until they enter a host, as they do not have eyes. They possess antennae
Antenna (biology)
Antennae in biology have historically been paired appendages used for sensing in arthropods. More recently, the term has also been applied to cilium structures present in most cell types of eukaryotes....

-like protrusions called palps, as well as osmosis
Osmosis
Osmosis is the movement of solvent molecules through a selectively permeable membrane into a region of higher solute concentration, aiming to equalize the solute concentrations on the two sides...

 node
Node
In general, a node is a localised swelling or a point of intersection .Node may refer to:In mathematics:*Node , behaviour for an ordinary differential equation near a critical point...

s, small organs that process nutrient
Nutrient
A nutrient is a chemical that an organism needs to live and grow or a substance used in an organism's metabolism which must be taken in from its environment. They are used to build and repair tissues, regulate body processes and are converted to and used as energy...

s in the Yeerks' native pools. Although the presence of a circulatory system
Circulatory system
The circulatory system is an organ system that passes nutrients , gases, hormones, blood cells, etc...

 of some kind is debatable, apparently Yeerks have no heart
Heart
The heart is a myogenic muscular organ found in all animals with a circulatory system , that is responsible for pumping blood throughout the blood vessels by repeated, rhythmic contractions...

s, as evidenced by the description of a human morphing into a Yeerk, in which the human heart stops and dissolves away completely.

Yeerks communicate in their natural state using a language of ultrasonic squeaks, and use sonar
Sonar
Sonar is a technique that uses sound propagation to navigate, communicate with or detect other vessels...

 to get a basic picture of the surroundings. The process of infestation by a Yeerk is not totally painless, but it does not hurt as much as it seems like it should, as a numbing chemical is secreted to anesthetize
Anesthetize
"Anesthetize" is a Porcupine Tree song. It is the third track on the 2007 album Fear of a Blank Planet. It is the longest song on this album, clocking in at 17:42, making Fear of a Blank Planet the studio album containing the longest composition since 1995's The Sky Moves Sideways "Anesthetize" is...

 and dilate the ear canal itself so that the slug-like Yeerk will not cause any physical harm to the host. It is able to manipulate and puncture a variety of alien ear canal structures including bone and membrane to reach the brain
Brain
The brain is the center of the nervous system in all vertebrate and most invertebrate animals—only a few primitive invertebrates such as sponges, jellyfish, sea squirts and starfishes do not have one. It is located in the head, usually close to primary sensory apparatus such as vision, hearing,...

. As the Yeerk reaches the eardrum and other ear canal structures, it pushes them aside.

After the process of infestation, the Yeerk flattens itself into what has been described as "3 parts, two wrinkled, one smooth", which is the brain. From there, all control is submitted involuntarily to the Yeerk (however, the host may fight and very rarely win). At this point, the host has no control over itself, no secrets, and no privacy. The Yeerk can even play with the memories of its former host. Although control can be returned to the host by the Yeerk, this does not occur often as most Yeerks prefer their parasitic relationship to a symbiotic
Symbiosis
Symbiosis is close and often long-term interaction between different biological species. In 1877 Bennett used the word symbiosis to describe the mutualistic relationship in lichens...

 one.

Yeerks cannot stay within their hosts for more than three Earth days. After this period of time, they need to bathe in a Yeerk pool and absorb Kandrona rays, the rays of their home sun. Without these rays, a Yeerk eventually starves.

However, there are two ways for Yeerks to survive without Kandrona rays, one terrible and cruel way being to eat other Yeerks. This cannibalism
Cannibalism
Cannibalism is the act or practice of humans eating the flesh of other human beings. It is also called anthropophagy...

 is not normal, a taboo and is only displayed by one Yeerk, Esplin 9466 the lesser (Visser Three
Visser Three
Visser Three, born as Esplin 9466 Primary and later known as Visser One, is a fictional character and the main antagonist of the sci-fi book series Animorphs, written by K.A. Applegate. He is the leader of the Yeerk forces on Earth, having inherited the planet from Edriss 562, who was Visser One at...

's twin sibling) after being cut off from Yeerk society by his twin. He kills Human-Controllers, opening their heads with brute force and eats the Yeerk inside with his maw.

Yeerks may also survive a lack of Kandrona rays by consuming instant maple
Maple
Acer is a genus of trees or shrubs commonly known as maple.Maples are variously classified in a family of their own, the Aceraceae, or together with the Hippocastanaceae included in the family Sapindaceae. Modern classifications, including the Angiosperm Phylogeny Group system, favour inclusion in...

 and ginger
Ginger
Ginger is the rhizome of the plant Zingiber officinale, consumed as a delicacy, medicine, or spice. It lends its name to its genus and family . Other notable members of this plant family are turmeric, cardamom, and galangal....

 oatmeal
Oatmeal
Oatmeal is ground oat groats , or a porridge made from oats . Oatmeal can also be ground oat, steel-cut oats, crushed oats, or rolled oats....

, although its effects are narcotic
Narcotic
The term narcotic originally referred medically to any psychoactive compound with any sleep-inducing properties. In the United States of America it has since become associated with opioids, commonly morphine and heroin and their derivatives, such as hydrocodone. The term is, today, imprecisely...

 and cause the Yeerk to become insane, dependent and trapped within its host indeterminately, without the need to feed in a Yeerk pool. The host may regain some control of its body from time to time, while the Yeerk has lapsed into narcotic-induced lack of control. Usually the Yeerk is not intelligible after full addiction
Substance dependence
The section about substance dependence in the Diagnostic and Statistical Manual of Mental Disorders does not use the word addiction at all. It explains:...

 has occurred, since the chemicals in the oatmeal damage part of its brain stem. The Animorphs discover this upon investigating a man named George Edelman who attempts to commit suicide
Suicide
Suicide is the act of intentionally causing one's own death. Suicide is often committed out of despair or attributed to some underlying mental disorder, such as depression, bipolar disorder, schizophrenia, alcoholism, or drug abuse...

. Edelman is put in an insane asylum, where the Animorphs follow him and discover the Yeerks' weakness to the oatmeal. The Yeerk in his head has succumbed to this weakness, and Edelman is able to speak and move freely, except when his Yeerk seizes control and rants unintelligibly in alien languages. Yeerks may intake oat flakes by way of their hosts. How the dietary fiber
Fiber
Fiber is a class of materials that are continuous filaments or are in discrete elongated pieces, similar to lengths of thread.They are very important in the biology of both plants and animals, for holding tissues together....

 exactly reaches the brain is unknown.

Reproduction

Yeerks reproduce through fusion. Three parent Yeerks merge into a single organism, which then breaks apart into hundreds of separate grubs, destroying the parents in the process. Sometimes twins are born when two Yeerks are born from one grub; thus Yeerks have no living parents.

Yeerks do not have different gender
Gender
Gender is a range of characteristics used to distinguish between males and females, particularly in the cases of men and women and the masculine and feminine attributes assigned to them. Depending on the context, the discriminating characteristics vary from sex to social role to gender identity...

s; presumably any three random Yeerks can reproduce. Nevertheless, the Yeerks normally use gender pronoun
Pronoun
In linguistics and grammar, a pronoun is a pro-form that substitutes for a noun , such as, in English, the words it and he...

s (he/she) in the novels based on their host's gender - usually by a human or Andalite
Andalite
The Andalites are a fictional alien race of grazers in the Scholastic book series Animorphs.-Biology:The Andalites are fictional aliens from the book series and TV series Animorphs....

 (Chapman/Iniss and Visser Three
Visser Three
Visser Three, born as Esplin 9466 Primary and later known as Visser One, is a fictional character and the main antagonist of the sci-fi book series Animorphs, written by K.A. Applegate. He is the leader of the Yeerk forces on Earth, having inherited the planet from Edriss 562, who was Visser One at...

/Alloran
Alloran-Semitur-Corrass
Alloran-Semitur-Corrass is a fictional character in the Animorphs series by K. A. Applegate. He is the host body of Visser Three, a high-ranking Yeerk and the primary antagonist of the series.-Character history:...

, or by the Yeerk adopting the gender personality of their host (Karen/Aftran or Taylor/Sub-Visser 51).

Hosts

So far, Yeerks have enslaved about 18 different kinds of alien species, completely or partially, including Hork-Bajir
Hork-Bajir
The Hork-Bajir are a race of aliens in the Animorphs novels.The Hork-Bajir are fictional aliens that are usually about seven feet tall. They are a dark shade of green and have three-toed theropod feet. Their necks are long and they have a mouth that resembles a falcon's beak with teeth. Their legs...

, Taxxon
Taxxon
The Taxxons are a fictional sentient race in the Animorphs book series by K.A. Applegate, one of the species conceptually created for the series. They resemble giant, centipedes, with the forward one-third portion of their body held erect. They move on many rows of needle-like legs and the legs...

s, Gedd
Gedd
Gedds are a species of aliens in the Animorphs book series. They evolved on the same planet as the Yeerks. The Gedds are a primate-like species, with terrible vision and bad motor skills. They served as the first hosts for the parasitic Yeerks....

s, the Nahara (never seen in the series), Leeran
Leeran
The Leerans are a fictional race of aliens from the Animorphs series by K.A. Applegate. They are described as a yellow amphibian species with tentacles for arms that resembles a manta ray or frog...

s, Garatrons, and of course, humans. According to a Yeerk named Temrash 144, the Yeerks may also have taken over creatures known as the Sstram and the Mak, neither of which is ever seen in the series.

The Yeerks also have the ability to infest Andalites; however, they are never successful in truly enslaving them. The only Andalite body that the Yeerks have ever manage to take over was War Prince Alloran-Semitur-Corrass
Alloran-Semitur-Corrass
Alloran-Semitur-Corrass is a fictional character in the Animorphs series by K. A. Applegate. He is the host body of Visser Three, a high-ranking Yeerk and the primary antagonist of the series.-Character history:...

, turning him into Visser Three
Visser Three
Visser Three, born as Esplin 9466 Primary and later known as Visser One, is a fictional character and the main antagonist of the sci-fi book series Animorphs, written by K.A. Applegate. He is the leader of the Yeerk forces on Earth, having inherited the planet from Edriss 562, who was Visser One at...

.

The Yeerks have a pseudo-diplomatic
Diplomacy
Diplomacy is the art and practice of conducting negotiations between representatives of groups or states...

 relationship with the metamorphic Skrit Na
Skrit Na
The Skrit Na are a race of aliens from the Animorphs book series by K.A. Applegate. They capture specimens from the many planets they visit and either perform strange medical procedures on them or put them in a zoo on their homeworld...

, but do not infest them due to the Skrit Na's lifestyle: The cockroach
Cockroach
Cockroaches are insects of the order Blattaria or Blattodea, of which about 30 species out of 4,500 total are associated with human habitations...

-like Skrit will sometimes unexpectedly cocoon itself and emerge as a Na over a year later, trapping any Yeerk inside, meaning death by starvation.

The Yeerks have also tried to enslave Hawjabrans and Ongachics, but they have failed on both accounts. One, because the Ongachic race is completely nomadic and spread out through the entire galaxy. Two, because Hawjabran brain
Brain
The brain is the center of the nervous system in all vertebrate and most invertebrate animals—only a few primitive invertebrates such as sponges, jellyfish, sea squirts and starfishes do not have one. It is located in the head, usually close to primary sensory apparatus such as vision, hearing,...

s are spread out in little nodes throughout their bodies, so the Yeerks can never completely control them.

The Yeerks also tried to infest horse
Horse
The horse is one of two extant subspecies of Equus ferus, or the wild horse. It is a single-hooved mammal belonging to the taxonomic family Equidae. The horse has evolved over the past 45 to 55 million years from a small multi-toed creature into the large, single-toed animal of today...

s, and did experiments on hammerhead shark
Hammerhead shark
The hammerhead sharks are a group of sharks in the family Sphyrnidae, so named for the unusual and distinctive structure of their heads, which are flattened and laterally extended into a "hammer" shape called a "cephalofoil". Most hammerhead species are placed in the genus Sphyrna while the...

s to increase their brain size so that they could use them as hosts in the war on the Leeran homeworld.

There are some species that the Yeerks do not know about, and therefore have not tried to infest, such as the Iskoort
Iskoort
The Iskoort are a fictional race of aliens from the Animorphs series by K.A. Applegate.They are made up of two parts - an "Isk" and a "Yoort". The Isk is the main physical body, and the Yoort is a slug which must leave the Isk every three days to soak up kandrona rays...

, since Yoort (yeerk-like part) are really like Yeerks, but civil, and they have never infested anyone else after the Isks (bio-robot bodies) were built for them. The Iskoort species is actually related to the Yeerks, even though they do not look at all similar, but not a lot of them know that, or have even heard of them.

Since the Yeerk has access to all parts of the brain (except with Hawjabrans), it is able to pass flawlessly as its host (now called a Controller) so that nobody else suspects that there is, in fact, a secret invasion of their planet. Another result of this is that hosts and Yeerks can sense each others' thoughts and feelings; while this usually is the extent to the mental connection, it seems hinted that the mental bond between the two can result in identity confusion, as in the case of Taylor. Another case of notice is that of Visser One, who, after marrying and having children through one of her hosts, felt an actual romantic and maternal bond to her "family."

Evidently, morph-capable Yeerks morph with their hosts and are extruded into zero-space along with the host's own morphed mass. This is shown in The Capture, when Jake, as a Controller, morphs into an ant
Ant
Ants are social insects of the family Formicidae and, along with the related wasps and bees, belong to the order Hymenoptera. Ants evolved from wasp-like ancestors in the mid-Cretaceous period between 110 and 130 million years ago and diversified after the rise of flowering plants. More than...

. An ant is far smaller than a Yeerk, so otherwise Jake would have been killed by destruction of his head.

List of Controllers

(Partial)
  • Jake's brother, Tom (Temrash 114, later unknown)
  • Andalite
    Andalite
    The Andalites are a fictional alien race of grazers in the Scholastic book series Animorphs.-Biology:The Andalites are fictional aliens from the book series and TV series Animorphs....

     Prince Alloran-Semitur-Corass (Esplin 9466 Primary; Visser Three
    Visser Three
    Visser Three, born as Esplin 9466 Primary and later known as Visser One, is a fictional character and the main antagonist of the sci-fi book series Animorphs, written by K.A. Applegate. He is the leader of the Yeerk forces on Earth, having inherited the planet from Edriss 562, who was Visser One at...

    , later Visser One)
  • Marco
    Marco (Animorphs)
    Marco is a fictional character from the sci-fi book series, Animorphs, written by K. A. Applegate. His last name is never mentioned.-Biography:...

    's mother, Eva (Edriss 562
    Edriss 562
    Edriss 562 is a Yeerk that controls Marco's mother Eva. For most of the series, her rank is Visser One. She is the subject of the novel Visser, which describes her rise to and dramatic fall from power...

    ; Visser One)
  • Mr. Hedrick Chapman (Iniss 226)
  • In #1: The Invasion, the kids are approached by a controller policeman. He later takes Cassie to the Yeerk pool, and he is mentioned by Tobias in book 13, The Change.
  • In #6: The Capture, Jake was a Controller (Temrash 114)
  • In #8: The Alien, Gary Kozlar (Eslin 359)
  • Park Rangers in books 9, 10, 16, and 14 were Controllers
  • In #12 The Reaction, Jeremy Jason McCole
  • In #13 The Change, a reporter mentioned by Tobias
  • In #14: The Unknown, 5 horses were Controllers
  • In #16: The Warning, Joe Bob Fenestre (Esplin 9466 Lesser)
  • In #19: The Departure, Cassie and a girl named Karen were Controllers (Aftran 942)
  • In #20 The Discovery and onwards, David's parents. After #22 The Solution their status is unknown.
  • In #22 The Solution, various policemen were Controllers
  • In #29: The Sickness, Ax
    Aximili-Esgarrouth-Isthill
    Aximili-Esgarrouth-Isthill is a fictional character from the sci-fi book series Animorphs.-Biography:Aximili is a young Andalite who becomes stranded on Earth when the Andalite Dome Ship GalaxyTree is shot down by Yeerk fighters...

     and Cassie were Controllers (Aftran 942), as was Mr. Tidwell (Illim)
  • In #33: The Illusion and #43: The Test, Taylor (Sub-Visser 19)
  • In #35: The Proposal, William Roger Tennant and a few TV people are human-controllers
  • In Megamorphs #4: Back to Before, Tobias was a Controller (Odret 177)
  • In #41: The Familiar, Cassie and Marco were Controllers.

Homeworld

The Yeerk homeworld has various satellite
Natural satellite
A natural satellite or moon is a celestial body that orbits a planet or smaller body, which is called its primary. The two terms are used synonymously for non-artificial satellites of planets, of dwarf planets, and of minor planets....

s, one of the natural ones is a moon
Moon
The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...

 called Madra. Yeerks inhabit a homeworld with a dark green and yellow, lightning
Lightning
Lightning is an atmospheric electrostatic discharge accompanied by thunder, which typically occurs during thunderstorms, and sometimes during volcanic eruptions or dust storms...

-torn sky. The ground is largely dark rich soil, and roughly circular Yeerk pools dot the surface, presumably connected to each other somehow, but this is not explained.

Individual pools have names, such as Sulp Niar. Yeerk pool water is a sludgy grey, filled with nutrient
Nutrient
A nutrient is a chemical that an organism needs to live and grow or a substance used in an organism's metabolism which must be taken in from its environment. They are used to build and repair tissues, regulate body processes and are converted to and used as energy...

s Yeerks need besides Kandrona rays. There are no more than a hundred animal species on the Yeerk homeworld, among them the Gedd
Gedd
Gedds are a species of aliens in the Animorphs book series. They evolved on the same planet as the Yeerks. The Gedds are a primate-like species, with terrible vision and bad motor skills. They served as the first hosts for the parasitic Yeerks....

s, which became the Yeerks' natural host, nearly a symbiotic
Symbiosis
Symbiosis is close and often long-term interaction between different biological species. In 1877 Bennett used the word symbiosis to describe the mutualistic relationship in lichens...

 relationship. The yeerk home world is surrounded by andalite ships that stop anything from coming in or out.

A Vanarx, also known as a "Yeerk-bane", is a big long purple tube-like creature that has a round mouth full of teeth, it is native to the Yeerk homeworld, and appears to be the Yeerks' only natural enemy. It latches itself onto the head of a Controller, sucking out the Yeerk inside and eating it. Visser Three morphs a Varnarx in Book #2: The Visitor as a means to eliminate useless subordinates without killing or hurting the host-body, and to scare Chapman.

History

Sometime on or before the Earth year 1966 (Yeerk date: Generation 685, mid-cycle; each Generation is roughly two Earth years and divided into three cycles), the first Andalite
Andalite
The Andalites are a fictional alien race of grazers in the Scholastic book series Animorphs.-Biology:The Andalites are fictional aliens from the book series and TV series Animorphs....

s arrived on the Yeerk homeworld, led by the Prince Seerow. Seerow pitied the Yeerks' physical drawbacks despite their capacity to learn, and set up the Andalite-Yeerk Peace and Cooperation Center on the Yeerk homeworld. He and other Andalites taught the Yeerks how to write down the Yeerk language phonetically, and taught them what lay beyond their green-clouded sky.

Once armed with the knowledge of space-faring technology and similar sciences, certain Yeerks rebelled against the Andalites, taking them off-guard and killing many people during the escape with several small Andalite ships and a few transports. The Yeerks stopped on the far side of their planet to siphon up large quantities of Yeerks from Yeerk pools before fleeing the planet, eventually to become the Yeerk Empire. Andalite forces began to patrol the Yeerk homeworld in orbit to make sure no more Yeerks entered, attempted contact, or attempted to leave.

The Yeerk Empire was gutted devastatingly with the death of seventeen thousand, three hundred and seventy-two Yeerks flushed from the Yeerk Pool Ship's onboard pool during the final blatant attack on Earth. The Empire's loss of Earth was caused largely by the Animorphs, and surrendered Yeerks were given amnesty
Amnesty
Amnesty is a legislative or executive act by which a state restores those who may have been guilty of an offense against it to the positions of innocent people, without changing the laws defining the offense. It includes more than pardon, in as much as it obliterates all legal remembrance of the...

 by the Andalite military if they became nothlits, or trapped in one morph forever. A single Blade Ship (holding the morphing cube
Escafil device
The Escafil device is a fictional technological apparatus from K.A. Applegate's popular children's book series Animorphs. It is the proper name for the "Andalite morphing cube", a device that when operated gives the user the ability to 'acquire' a copy of DNA patterns from any animal that physical...

) escaped with the intent of creating a new Yeerk Empire, and allied with a dangerous, cult
Cult
The word cult in current popular usage usually refers to a group whose beliefs or practices are considered abnormal or bizarre. The word originally denoted a system of ritual practices...

-like, otherworldly entity known only as The One. The One captured Ax
Aximili-Esgarrouth-Isthill
Aximili-Esgarrouth-Isthill is a fictional character from the sci-fi book series Animorphs.-Biography:Aximili is a young Andalite who becomes stranded on Earth when the Andalite Dome Ship GalaxyTree is shot down by Yeerk fighters...

 when he boarded a dead-in-space ship which concealed the Blade Ship. Not much is known about The One except that it is possible he, or it, is allied with the Kelbrid, he/it is possibly more powerful than the Ellimist, and he/it can assimilate other life forms.

Culture

Yeerk names end in numbers, which designate which number grub they are (i.e. Aftran 942 is the nine hundred forty second grub to emerge from the Aftran tri-parent). In the case of twin, both are given the same number, which ends in a double number. For example, Visser Three
Visser Three
Visser Three, born as Esplin 9466 Primary and later known as Visser One, is a fictional character and the main antagonist of the sci-fi book series Animorphs, written by K.A. Applegate. He is the leader of the Yeerk forces on Earth, having inherited the planet from Edriss 562, who was Visser One at...

 is Esplin 9466 Primary, and his brother is Esplin 9466 Secondary. The higher twin is considered to be superior to the other.

In the Yeerk military, each of them is ranked one after the other, and are referred to by title and number. The lowest rank apparently does not earn the person a title (for example, the Yeerk Essam 293 is only ever referred to by name). The next rank up is Sub-Visser, which is equivalent to a colonel
Colonel
Colonel , abbreviated Col or COL, is a military rank of a senior commissioned officer. It or a corresponding rank exists in most armies and in many air forces; the naval equivalent rank is generally "Captain". It is also used in some police forces and other paramilitary rank structures...

 or some such officer rank; after being promoted above sub-visser level, Yeerks may become one of 47 Vissers, which are equivalent to general
General
A general officer is an officer of high military rank, usually in the army, and in some nations, the air force. The term is widely used by many nations of the world, and when a country uses a different term, there is an equivalent title given....

s or to Andalite
Andalite
The Andalites are a fictional alien race of grazers in the Scholastic book series Animorphs.-Biology:The Andalites are fictional aliens from the book series and TV series Animorphs....

 Princes.

As a note, earlier in the series, the name number and rank number were the same thing (for example, Temrash 252 was promoted to being Temrash 114) - Vissers were of the numbers from 1 to 47 and Sub-Vissers from 47 to 100; however, this was later retcon
Retcon
Retroactive continuity is the alteration of previously established facts in a fictional work. Retcons are done for many reasons, including the accommodation of sequels or further derivative works in a series, wherein newer authors or creators want to revise the in-story history to allow a course...

ned by K.A. Applegate with Yeerks remaining with the same number as their "name", no matter what their rank. For example, Visser Three's "name" is still Esplin 9466 Primary, while Visser Three is his rank.

The head of the Yeerk Empire is the Council of Thirteen, the leader of which is the enigmatic Yeerk Emperor; however, to prevent assassination, his identity is never known by anyone but the Councilors. Of the thirteen council members, two remain always concealed. They wear very dark red, almost black, robes, and those Council members who have Hork-Bajir
Hork-Bajir
The Hork-Bajir are a race of aliens in the Animorphs novels.The Hork-Bajir are fictional aliens that are usually about seven feet tall. They are a dark shade of green and have three-toed theropod feet. Their necks are long and they have a mouth that resembles a falcon's beak with teeth. Their legs...

 hosts wear a thin mesh under the robes to prevent them from tearing. Thirteen seems to be a symbolic number for the Yeerks, as trials also have thirteen guards on duty.

There is a faction of Yeerks who have formed an entity known as the Yeerk Peace Faction, which opposes the wars led by the Empire in secret and whose members, who may be Yeerks and/or their hosts, oppose involuntary infestation.

Iskoort

There exists an offshoot of the Yeerks that was taken from the homeworld millennia ago: the Yoort. The Yoort have long since changed from taking hosts, and have created symbionts; they genetically engineered a species,the Isk, with whom they have a symbiotic
Symbiosis
Symbiosis is close and often long-term interaction between different biological species. In 1877 Bennett used the word symbiosis to describe the mutualistic relationship in lichens...

 relationship. The joint species is called Iskoort
Iskoort
The Iskoort are a fictional race of aliens from the Animorphs series by K.A. Applegate.They are made up of two parts - an "Isk" and a "Yoort". The Isk is the main physical body, and the Yoort is a slug which must leave the Isk every three days to soak up kandrona rays...

.

Before becoming symbionts, the Yoorts (like the Yeerks) believed that conquest was the way forward. But over time, they realized that this wouldn't be beneficial, because the Isk (Iskoort) are mostly concerned with profit and society. They made a symbiotic relationship so that the Yoort cannot survive without the Isk and the Isk cannot survive without the Yoort.

The Ellimist
Ellimist
The Ellimist is a fictional character from the science fiction novel series Animorphs.The Ellimist is an almost god-like being, displaying many reality warping powers, though it is stated several times that while he appears to be, he is not omnipotent. By standard values, the Ellimist is a force of...

 sent the Animorphs to their homeworld in hopes to save the species so that someday the Yeerks would meet Iskoorts, and the Yeerks would realize there is a better way to live than parasitism
Parasitism
Parasitism is a type of symbiotic relationship between organisms of different species where one organism, the parasite, benefits at the expense of the other, the host. Traditionally parasite referred to organisms with lifestages that needed more than one host . These are now called macroparasites...

.

Yeerk technology

Yeerk technology is largely stolen from other races, although the Yeerks themselves appear to have a great capacity to learn and create new technology with pieces of alien technology. Yeerk technology and ships include:
  • Dracon beams – Hand-held or cannon weapons that emit a painful red beam of energy. Powered by energy cells, Dracon beams have ten settings, the most powerful of which can punch a hole straight through ten feet of solid titanium
    Titanium
    Titanium is a chemical element with the symbol Ti and atomic number 22. It has a low density and is a strong, lustrous, corrosion-resistant transition metal with a silver color....

    . They are modified from Andalite
    Andalite
    The Andalites are a fictional alien race of grazers in the Scholastic book series Animorphs.-Biology:The Andalites are fictional aliens from the book series and TV series Animorphs....

     shredders by combining them with Ongachic particle technology to make it more painful.
  • Yeerk hand-held computers – Small green squares with a holographic
    Holography
    Holography is a technique that allows the light scattered from an object to be recorded and later reconstructed so that when an imaging system is placed in the reconstructed beam, an image of the object will be seen even when the object is no longer present...

    , translucent screen.
  • Hunter-killer robots – Medium-sized spheres with a single lens that senses movement as a threat, and fires a killing Dracon beam at the target.
  • Killing cylinder – An assassination
    Assassination
    To carry out an assassination is "to murder by a sudden and/or secret attack, often for political reasons." Alternatively, assassination may be defined as "the act of deliberately killing someone, especially a public figure, usually for hire or for political reasons."An assassination may be...

     device concealed within a small metal cylinder; when pressed to the back of a host's neck, it kills both Yeerk and host instantly.
  • Genetic scanner – Small hand-held device that scans the target for genetic makeup, but does not harm the target. It was modified from Andalite technology.
  • Zero-space engines – Allow a ship to jump from real space to zero-space, taking advantage of the curvature of space to travel great distances much more quickly. It was blatantly stolen from Andalites.
  • Anti-morphing ray – A machine that forces a creature to revert its DNA
    DNA
    Deoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms . The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in...

     pattern from a morph to that of its natural cell
    Cell (biology)
    The cell is the basic structural and functional unit of all known living organisms. It is the smallest unit of life that is classified as a living thing, and is often called the building block of life. The Alberts text discusses how the "cellular building blocks" move to shape developing embryos....

    s. Only a prototype was constructed; however, while it might have worked, the Animorphs tricked Visser Three
    Visser Three
    Visser Three, born as Esplin 9466 Primary and later known as Visser One, is a fictional character and the main antagonist of the sci-fi book series Animorphs, written by K.A. Applegate. He is the leader of the Yeerk forces on Earth, having inherited the planet from Edriss 562, who was Visser One at...

     into thinking it didn't, and subsequently the project was abandoned, its creators put to death.
  • Yeerk torture device – One of presumably many, it consists of three buttons that focus on a box where the target lies. The Yeerks rely on their knowledge of all things neural to force the target to feel extreme pain, extreme happiness, or both at the same time.
  • Bug fighters – Basic maximum-of-three-person fighters that resemble a black, oval-shaped beetle
    Beetle
    Coleoptera is an order of insects commonly called beetles. The word "coleoptera" is from the Greek , koleos, "sheath"; and , pteron, "wing", thus "sheathed wing". Coleoptera contains more species than any other order, constituting almost 25% of all known life-forms...

     or other insect, with two eye-like windows and two serrated spears (the Dracon cannon) jutting out from its front end. The interior is large enough for three crewmembers of various species to walk around in, with a weapons station and navigational controls (the latter often handled by a Taxxon
    Taxxon
    The Taxxons are a fictional sentient race in the Animorphs book series by K.A. Applegate, one of the species conceptually created for the series. They resemble giant, centipedes, with the forward one-third portion of their body held erect. They move on many rows of needle-like legs and the legs...

    ). It is modified from Andalite tail-fighters, and inspired by the Hork-Bajir
    Hork-Bajir
    The Hork-Bajir are a race of aliens in the Animorphs novels.The Hork-Bajir are fictional aliens that are usually about seven feet tall. They are a dark shade of green and have three-toed theropod feet. Their necks are long and they have a mouth that resembles a falcon's beak with teeth. Their legs...

     homeworld, where the Bug fighters were first built.
  • Blade Ships – Resemble a black medieval battle-axe, with two broad axe-like wings and a long "handle" with a diamond-shaped bridge on the end. Blade Ships are typically assigned to Vissers.
  • Pool Ships – Huge, round, bloated, black ships with three spider-like legs are the engines and a series of thick tentacles hanging from the bottom (sensors and weapons); they are often known as Mother Ships.
  • Cruiser-class ships – Shaped like a V or a boomerang. These ships fly with the two pronged ends forward, which hold Dracon cannons.
  • Truck Ships – Shaped almost like large black metal manta ray
    Manta ray
    The manta ray is the largest species of the rays. The largest known specimen was more than across, with a weight of about . It ranges throughout waters of the world, typically around coral reefs...

    s. They are used to siphon large quantities of water or other supplies. These were stolen from Andalites.
  • Nova-class Empire ship - Larger than Visser Three's Blade Ship, it has eight pods arranged around a central, cylindrical core. Four massive engines bunch up at its rear, blazing a blue fire. Appears only in book 30
    The Reunion (Animorphs)
    The Reunion is the thirtieth book in the Animorphs series, authored by K.A. Applegate. It is known to have been ghostwritten by Elise Donner. It is narrated by Marco.-Plot summary:...

    , under the command of Visser One
    Edriss 562
    Edriss 562 is a Yeerk that controls Marco's mother Eva. For most of the series, her rank is Visser One. She is the subject of the novel Visser, which describes her rise to and dramatic fall from power...

    .

Yeerk terminology

  • Andalite bandit – The common term by which the Yeerks refer to the Animorphs, believing them to be Andalite
    Andalite
    The Andalites are a fictional alien race of grazers in the Scholastic book series Animorphs.-Biology:The Andalites are fictional aliens from the book series and TV series Animorphs....

     survivors of Prince Elfangor
    Elfangor-Sirinial-Shamtul
    Elfangor-Sirinial-Shamtul is a character in K. A. Applegate's book series Animorphs. He is of an alien race known as the Andalites. His adventures are highlighted in the book called The Andalite Chronicles, which takes place before the main Animorphs series.Elfangor is an Andalite war-prince, who...

    's Dome ship due to their morphing abilities.
  • Anti-Morphing Ray (AMR) – A Yeerk-developed device which can detect morphing energy and reverse the morphing process. Only one was constructed; the prototype was destroyed following an infiltration attempt by the Animorphs. The technology was abandoned by the Yeerks despite it possibly functioning correctly; the Animorphs deceived the Yeerks into believing that this was not the case.
  • Blade shipVisser Three
    Visser Three
    Visser Three, born as Esplin 9466 Primary and later known as Visser One, is a fictional character and the main antagonist of the sci-fi book series Animorphs, written by K.A. Applegate. He is the leader of the Yeerk forces on Earth, having inherited the planet from Edriss 562, who was Visser One at...

    's private command ship. The Blade ship is the visser's usual means of transportation. The ship is described as "shaped like a battle-axe" with its weapons section in the rear, and is colored jet black.
  • Blue Band Squad - An elite Hork-Bajir
    Hork-Bajir
    The Hork-Bajir are a race of aliens in the Animorphs novels.The Hork-Bajir are fictional aliens that are usually about seven feet tall. They are a dark shade of green and have three-toed theropod feet. Their necks are long and they have a mouth that resembles a falcon's beak with teeth. Their legs...

     unit. These Controllers are highly trained, and are much faster and much stronger than the average shock trooper. They also wear blue bands on their arms, hence their group's name. The squad leader's name is Grath, which could either be the name of the Yeerk or the Hork-Bajir he controls.
  • Bug fighter – The standard Yeerk fighter craft. The Bug fighter resembles a jet-black cockroach
    Cockroach
    Cockroaches are insects of the order Blattaria or Blattodea, of which about 30 species out of 4,500 total are associated with human habitations...

     without legs. The 'head' of the fighter has two long, serrated, lance-like projections, which house the fighter's complement of Dracon beams.
  • Controller – A term used to describe a creature under the control of a Yeerk parasite.
  • Council of Thirteen – The head of the Yeerk government. This supreme body of leaders is composed of thirteen members, each with their own host body. Council members dress in elaborate robes. One of the Council members is the Emperor, but the leader is known only to the other Council members.
  • Dapsen – According to Ax
    Aximili-Esgarrouth-Isthill
    Aximili-Esgarrouth-Isthill is a fictional character from the sci-fi book series Animorphs.-Biography:Aximili is a young Andalite who becomes stranded on Earth when the Andalite Dome Ship GalaxyTree is shot down by Yeerk fighters...

    , dapsen is not a very polite word. This word was used to name a Yeerk front organization, Dapsen Logging Company. This leads the Animorphs to believe that "The Yeerks may have a sense of humor after all..."
  • Dracon beam – The main particle weapon used by the Yeerks. It is deployed in hand-held form as well as more powerful starship-mounted variants. The hand-held Dracon beam is capable of punching through significant amounts of titanium
    Titanium
    Titanium is a chemical element with the symbol Ti and atomic number 22. It has a low density and is a strong, lustrous, corrosion-resistant transition metal with a silver color....

    . A Dracon beam has multiple power settings, rendering it capable of simply stunning or completely vapourizing organic matter. Yeerk Dracon beams were most likely adapted from the Andalites' shredders.
  • Alien Species Grouping System – The Yeerks have a grouping system for different alien species. They are arranged into five Classes:
  1. Physically unfit species, such as Hawjabrans, Mortrons and Skrit Na
    Skrit Na
    The Skrit Na are a race of aliens from the Animorphs book series by K.A. Applegate. They capture specimens from the many planets they visit and either perform strange medical procedures on them or put them in a zoo on their homeworld...

     are described as Class One aliens.
  2. Aliens that can be infested, but suffer from physiological disadvantages, like Taxxons and Gedds, are considered Class Two species.
  3. Class Three aliens such as Hork-Bajir are excellent for infestation, but exist in low numbers and do not breed quickly.
  4. Andalites are plentiful and would make good hosts, but are very difficult to defeat, and as such are Class Four species. In Visser
    Visser
    Visser may refer to:* Visser, a companion novel from the Animorphs sci-fi series, and also a term used within the continuity of the series to denote a Yeerk of high status or rank in the military of the Yeerk Empire...

    , it is mentioned that Class Four species are out of reach, for now.
  5. Class Five aliens are those that are physically fit, can be infested, are extremely adaptable, are numerous, breed quickly, and are unable to resist the Yeerks. Humans were originally thought to be in this category, but were later moved down to Class Four.
    • Formula 71 – A chemical designed to destroy free will
      Free will
      "To make my own decisions whether I am successful or not due to uncontrollable forces" -Troy MorrisonA pragmatic definition of free willFree will is the ability of agents to make choices free from certain kinds of constraints. The existence of free will and its exact nature and definition have long...

      . However, it is impossible to do such a thing to any species. The Yeerks tried putting it in hamburger
      Hamburger
      A hamburger is a sandwich consisting of a cooked patty of ground meat usually placed inside a sliced bread roll...

       meat in order to speed up the invasion of Earth.
    • Fugue – 'The fugue' is the death phase, occurring at the end of the three days of a Yeerk's Kandrona starvation. In its final moments, a Yeerk recalls its memories and those of its former hosts, before leaving the host and disintegrating.
    • Gashad – A warrant issued by the Council of Thirteen to execute a subject on sight.
    • Gleet BioFilter – The Gleet BioFilter is stolen technology, first developed by the Andalites. The purpose of a BioFilter is to eradicate all organic life forms that are not registered in its DNA database. Gleet BioFilters are typically positioned at key entry points to sensitive areas, such as the Yeerk pool, in order to ward off spies. First appeared in book 17
      The Underground (Animorphs)
      The Underground is the seventeenth book in the Animorphs series, written by K.A. Applegate. It is narrated by Rachel.-Plot summary:...

      .
    • Happy Meal
      Happy Meal
      A "Happy Meal" is a meal specifically marketed at children, sold at the fast-food chain McDonald's since June 1979. A toy is typically included with the food, both of which are usually contained in a small box or paper bag with the McDonald's logo....

       with Extra Happy
      – The secret password to enter the Yeerk pool at McDonald's
      McDonald's
      McDonald's Corporation is the world's largest chain of hamburger fast food restaurants, serving around 64 million customers daily in 119 countries. Headquartered in the United States, the company began in 1940 as a barbecue restaurant operated by the eponymous Richard and Maurice McDonald; in 1948...

       fast food restaurants. (Book only, the TV series modifies this to a generic diner and the password being "Cheeseburger, hold the cheese.")
    • Kandrona – The name of the sun of the Yeerk homeworld. Yeerks must bask in its light every three days in order to obtain essential nutrients, much like the human ability to synthesize vitamin D2 by solar radiation. When away from their homeworld, the Yeerks utilize a Kandrona Particle Generator, which simulates the rays of their home sun, to replenish themselves. Kandrona devices can have many different sizes in order to serve one or more Yeerk pools with different capacities. Known large-size Kandronas were located on the EGS Tower in the Animorphs' home city, and aboard the Yeerk Pool Ship.
    • Kandrona Particle Generators, Emergency – A one-use, small Yeerk pool made for emergencies. These are designed to make it more or less easy for the Yeerks to carry around with them. They are usually used by Yeerks on the run.
    • Madra - The tiny, bright moon of the Yeerk home world.
    • Operation 9466 – A failed Yeerk plan to weaken Earth by causing World War III
      World War III
      World War III denotes a successor to World War II that would be on a global scale, with common speculation that it would be likely nuclear and devastating in nature....

      .
    • Project Obedience – Codename for a Yeerk attempt to conquer Earth by stripping humans of their free will. It failed miserably because sentient beings are inseparable from free will. Appears in book 28
      The Experiment (Animorphs)
      The Experiment is the twenty-eighth book in the Animorphs series, written by K.A. Applegate. It is known to have been ghostwritten by Amy Garvey. It is narrated by Ax.The front cover quote is "Change is a good thing...

      .
    • Ramonite - First seen in Megamorphs 1
      The Andalite's Gift (Megamorphs)
      #1: The Andalite's Gift is the first book in the series, a set of companion books to the Animorphs series. With respect to continuity, it takes place between book #7, The Stranger and book #8, The Alien...

      , a Ramonite box is described by Ax as "seamless walls on all sides." It is "a metal that can stretch open or be made clear or opaque by molecular realignment." The Yeerks use it for imprisoning morph-capable individuals.
    • The Sharing – The Yeerk front organization
      Front organization
      A front organization is any entity set up by and controlled by another organization, such as intelligence agencies, organized crime groups, banned organizations, religious or political groups, advocacy groups, or corporations...

      . On the surface, the Sharing resembles the Scout movement
      Scouting
      Scouting, also known as the Scout Movement, is a worldwide youth movement with the stated aim of supporting young people in their physical, mental and spiritual development, that they may play constructive roles in society....

      : family, friends, cooperation. However, the Sharing is revealed to be an organization dedicated to advancing the Yeerk invasion on Earth, screening potential Controllers from the larger Sharing membership.
    • Vanarx – A large, translucent purple predatory worm that attaches itself to a Controller's head and sucks out the Yeerk within. It apparently comes from the Yeerk homeworld. It is also known as a 'Yeerk-bane.'
    • Veleek – The Yeerk word for "pet"; the name given by Visser Three
      Visser Three
      Visser Three, born as Esplin 9466 Primary and later known as Visser One, is a fictional character and the main antagonist of the sci-fi book series Animorphs, written by K.A. Applegate. He is the leader of the Yeerk forces on Earth, having inherited the planet from Edriss 562, who was Visser One at...

       to the Saturn
      Saturn
      Saturn is the sixth planet from the Sun and the second largest planet in the Solar System, after Jupiter. Saturn is named after the Roman god Saturn, equated to the Greek Cronus , the Babylonian Ninurta and the Hindu Shani. Saturn's astronomical symbol represents the Roman god's sickle.Saturn,...

      ian monster in The Andalite's Gift
      The Andalite's Gift (Megamorphs)
      #1: The Andalite's Gift is the first book in the series, a set of companion books to the Animorphs series. With respect to continuity, it takes place between book #7, The Stranger and book #8, The Alien...

      .
    • Visser – A high rank in the Yeerk hierarchy. It equates more or less to a general
      General
      A general officer is an officer of high military rank, usually in the army, and in some nations, the air force. The term is widely used by many nations of the world, and when a country uses a different term, there is an equivalent title given....

       or an Andalite prince. There are forty-seven Vissers, and many more Sub-Vissers, who are equivalent to colonel
      Colonel
      Colonel , abbreviated Col or COL, is a military rank of a senior commissioned officer. It or a corresponding rank exists in most armies and in many air forces; the naval equivalent rank is generally "Captain". It is also used in some police forces and other paramilitary rank structures...

      s.
    • Yeerk Peace Movement – Underground movement opposed to the taking of unwilling hosts. It was founded by Aftran 942.
    • Yeerk Pool – A body of liquid of variable size that simulates the conditions of the Yeerk homeworld. Controllers return to their local Yeerk pool every three days, so that the Yeerk can be let out into the pool, allowing it to absorb nutrients from the liquid and rays from the Kandrona device.

The Sharing

The Sharing is the front organization
Front organization
A front organization is any entity set up by and controlled by another organization, such as intelligence agencies, organized crime groups, banned organizations, religious or political groups, advocacy groups, or corporations...

 for the Yeerks. The purpose of The Sharing is to persuade humans to submit to this infestation voluntarily. Some humans do submit voluntarily, while the Yeerks simply force infestation on those who do not. Members are not allowed to remain free indefinitely, and all members of The Sharing, bar those who have newly joined, are under the control of a Yeerk slug.

The Sharing uses psychological manipulation
Psychological manipulation
Psychological manipulation is a type of social influence that aims to change the perception or behavior of others through underhanded, deceptive, or even abusive tactics. By advancing the interests of the manipulator, often at the other's expense, such methods could be considered exploitative,...

s similar to those used by the cult-like organizations
Scientology
Scientology is a body of beliefs and related practices created by science fiction and fantasy author L. Ron Hubbard , starting in 1952, as a successor to his earlier self-help system, Dianetics...

 in the real world, although, unlike most cults, The Sharing is successful in making itself appear mainstream to the larger human society. The head of The Sharing is a high-ranking Controller named Hedrick Chapman. The Sharing was founded by Edriss 562
Edriss 562
Edriss 562 is a Yeerk that controls Marco's mother Eva. For most of the series, her rank is Visser One. She is the subject of the novel Visser, which describes her rise to and dramatic fall from power...

 when she was controlling a man named Lawrence Alter/Lore David Altman. She later killed Lore so that he would be revered as the founder of the group.

See also

  • Parasite
  • Alien invasion
    Alien invasion
    The alien invasion is a common theme in science fiction stories and film, in which extraterrestrial life invades Earth either to exterminate and supplant human life, enslave it under a colonial system, harvest humans for food, steal the planet's resources, or destroy the planet altogether.The...

  • The Goa'uld
    Goa'uld
    The Goa'uld are a fictional symbiotic race of ancient astronauts from the American-Canadian military science fiction television franchise Stargate. The Goa'uld are parasites from the planet P3X-888, integrated within a host, most of the time human. The resulting creatures are a powerful race bent...

     from Stargate SG-1
    Stargate SG-1
    Stargate SG-1 is a Canadian-American adventure and military science fiction television series and part of Metro-Goldwyn-Mayer's Stargate franchise. The show, created by Brad Wright and Jonathan Glassner, is based on the 1994 feature film Stargate by Dean Devlin and Roland Emmerich...

    , which are extremely similar in nature (although a Goa'uld can stay in a host for as long as it likes. In addition the Iskoort are similar to the "Tok'ra
    Tok'ra
    The Tok'ra are a fictional alien race on the science fiction television series Stargate SG-1. They first appear in the season 2 episode . In the show, the Tok'ra are biologically the same species as the Goa'uld who inhabit human hosts in a symbiotic relationship, and are opposed to the evil System...

    " in the Stargate universe.)
  • The Zerg from StarCraft
    StarCraft
    StarCraft is a military science fiction real-time strategy video game developed by Blizzard Entertainment. The first game of the StarCraft series was released for Microsoft Windows on 31 March 1998. With more than 11 million copies sold worldwide as of February 2009, it is one of the best-selling...

  • The Ceti eel from Star Trek II: The Wrath of Khan
    Star Trek II: The Wrath of Khan
    Star Trek II: The Wrath of Khan is a 1982 American science fiction film released by Paramount Pictures. The film is the second feature based on the Star Trek science fiction franchise. The plot features James T...

  • Conspiracy (Star Trek) from Star Trek: The Next Generation
    Star Trek: The Next Generation
    Star Trek: The Next Generation is an American science fiction television series created by Gene Roddenberry as part of the Star Trek franchise. Roddenberry, Rick Berman, and Michael Piller served as executive producers at different times throughout the production...

  • The six Migar species from the television series Tracker
    Tracker (TV series)
    Tracker is a 2001 Canadian science fiction television series starring Adrian Paul and Amy Price-Francis. The series is based on a short story by Gil Grant and Jeannine Renshaw...

     (although in this case, the human host dies; the alien is only using the body)
  • The black oil
    Black Oil
    Black Oil may refer to:* Black Oil , an alien virus in the X-Files episode The Colonist* a sunflower variety...

     from The X-Files
    The X-Files
    The X-Files is an American science fiction television series and a part of The X-Files franchise, created by screenwriter Chris Carter. The program originally aired from to . The show was a hit for the Fox network, and its characters and slogans became popular culture touchstones in the 1990s...

  • The unnamed aliens from Robert A. Heinlein
    Robert A. Heinlein
    Robert Anson Heinlein was an American science fiction writer. Often called the "dean of science fiction writers", he was one of the most influential and controversial authors of the genre. He set a standard for science and engineering plausibility and helped to raise the genre's standards of...

    's novel The Puppet Masters
    The Puppet Masters
    The Puppet Masters is a 1951 science fiction novel by Robert A. Heinlein in which American secret agents battle parasitic invaders from outer space...

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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